Cadmium enhances biochar-based carbon sequestration in soils via cation bridging and microbial toxicity

[Geoengineering News]

https://www.maxapress.com/article/doi/10.48130/bchax-0026-0016

Authors: Huayue Nie, Chang Shen, Xuliang Han, Zikai Lai, Mingwei Chen, Chenxiao Hu, Lanfang Han

Published online: 11 June 2026

Abstract

Biochar is acclaimed for its dual capacity to sequester carbon and immobilize heavy metals in soils. Here, through a 60-day incubation using δ13C isotopic tracing with cadmium (Cd) pollution, we demonstrated that Cd contamination enhanced biochar's carbon sequestration capability by suppressing the mineralization of both biochar and native soil organic carbon. Mechanistic investigations revealed that Cd promoted macroaggregate formation in biochar soils and enhanced biochar's adsorption capacity for dissolved organic carbon via cation bridging, as evidenced by density functional theory calculations; the adsorbed Cd exhibited toxicity to microbes residing on the biochar particles, resulting in decreased microbial biomass carbon. These synergistic mechanisms likely drive the enhanced biochar-based carbon sequestration observed in Cd-contaminated soils.

Source: BiocharX